Propositional phrase: a modifying phrase consisting of a preposition and its object.
Example: According to the weather forecast
In this sentence, according is the propositional phrase.
More examples: about, after, at, before, behind, by, during, for, from, in, of, over, past, to, under, up, and with.
These are common propositional phrases.
Now that you have two examples, you should be able to find the propositional phrase!